1. Field of the Invention
The present invention relates to a method for producing boiled egg-like foods utilizing irradiation of far infrared rays and to an apparatus for producing the same.
2. Background Information
Chicken eggs have been used as valuable nutrition sources for daily life. Chicken eggs are often boiled for eating and used, for example, as side dishes of a packed or box lunch for a school children""s excursion or athletic meet. When boiled eggs are made in the home, in general, raw eggs are placed in a pot or the like and heated by boiling water.
After chicken eggs have been boiled for eating, the freshness of the boiled eggs tend to deteriorate rapidly. Accordingly, boiled eggs should be eaten soon after boiling before the freshness is deteriorated. However, people sometimes miss the opportunity to eat the boiled eggs before they lose freshness and even do not eat them before they eventually rot.
Thus, it is believed that boiled eggs are hardly stored for a long period of time under natural conditions as well as in a refrigerator due to the problem of freshness. If a long time has passed before boiled eggs are eaten or if the boiled eggs are stored without taking the environmental temperature into consideration, rotting of the boiled eggs is accelerated. It is understood that eating boiled eggs in a rotted state can endanger the health of individuals.
It is believed that eggs boiled by boiling water are low in storability, since miscellaneous bacteria tends to invade through fine pores of the eggshells. Particularly, when the boiled eggs are cooled by cold water, the invasion of miscellaneous bacteria is substantial, thereby further lowering the storability of boiled eggs.
As mentioned above, chicken eggs are used for various styles and purposes in the field of processed foods, but boiled eggs are limited in uses at the present stage. If long term storage of boiled egg-like processed foods becomes possible, these can be widely used for daily demand as well as nourishing foods at the time of emergency during disasters such as earthquakes or floods.
The present invention has been developed in view of the foregoing problems in the conventional art.
It is an object of the present invention to provide a method for producing boiled egg-like foods which can be stored for a long period of time under natural conditions without generating nasty smell and letting the eggs rot while maintaining the taste of the boiled eggs.
Another object of the present invention is to provide an apparatus for producing boiled egg-like foods and which has a simple construction, is easy to use and is economical to manufacture.
The foregoing and other objects of the present invention are carried out by a method for producing boiled egg-like foods comprising the steps of heating eggs, such as chicken eggs, under a dry-heating condition at a temperature of from 65 to 90xc2x0 C., and irradiating the eggs thoroughly with far infrared electromagnetic waves having a wavelength in the range of from 3 to 30 xcexcm. 
According to the present invention, upon heating of the egg, the irradiated far infrared electromagnetic waves reach the depth of the egg, act on the molecules of water in the egg yolk, and initiate thermal motion, whereby the temperature of the egg yolk will be raised and coagulation will start. Further, carbon dioxide contained in the white part of the egg is expanded by heating, and the volume of the egg is increased. At the same time, sulfur-containing amino acid contained in the egg white is decomposed by heating and hydrogen sulfide is generated. The expanded carbon dioxide comes out of the egg through the pores of the eggshell together with the hydrogen sulfide and the egg white is coagulated.
By the foregoing process according to the present invention, the pores of the egg shell are hardly invaded by miscellaneous bacteria during coagulation of the egg white. Further, sterilization of the egg is also achieved during irradiation with the far infrared rays. By heating and irradiating the eggs with far infrared rays for about 1 to 2 hours, for example, the eggs are processed into boiled egg-like foods. The boiled egg-like foods produced by the method according to the present invention withstand storage at room temperature for about 30 to 50 days.
In another aspect, the present invention is directed to an apparatus for producing boiled egg-like foods. The apparatus comprises a case having a space surrounded by metal plates for irradiating far infrared rays and to which heating sources are closely attached, and an egg tray disposed within the case for supporting eggs to be subjected to the heating and irradiation process described above. The apparatus is constructed such that the surfaces of the eggs placed in the egg tray can be uniformly irradiated with the far infrared rays.